【DB笔试面试457】如何判断一个字符串是否含有中文汉字？

SYS@lhrdb> CREATE TABLE AA (COL   VARCHAR2(255));
Table created.
SYS@lhrdb> INSERT INTO AA (COL) VALUES ('1');
1 row created.
SYS@lhrdb> INSERT INTO AA (COL) VALUES ('２'); --全角字符
1 row created.
SYS@lhrdb> INSERT INTO AA (COL) VALUES ('小麦苗');
1 row created.
SYS@lhrdb> COMMIT;
Commit complete.
SYS@lhrdb> SELECT * FROM AA;   
COL
----------
1
２
小麦苗
SYS@lhrdb> COL COL FORMAT A10
SYS@lhrdb> COL SINGLE_COL  FORMAT A10
SYS@lhrdb> SELECT A.COL COL,
  2         TO_SINGLE_BYTE(A.COL) SINGLE_COL,
  3         LENGTH(A.COL) LENGTH_COL,
  4         LENGTHB(A.COL) LENGTHB_COL,
  5         LENGTH(TO_SINGLE_BYTE(A.COL)) SINGLE_LENGTH_COL,
  6         LENGTHB(TO_SINGLE_BYTE(A.COL))  SINGLE_LENGTHB_COL
  7    FROM AA A
  8   WHERE LENGTHB(A.COL) <> LENGTH(A.COL)
  9     AND LENGTHB(TO_SINGLE_BYTE(A.COL)) <> LENGTH(TO_SINGLE_BYTE(A.COL));
COL        SINGLE_COL LENGTH_COL LENGTHB_COL SINGLE_LENGTH_COL SINGLE_LENGTHB_COL
---------- ---------- ---------- ----------- ----------------- ------------------
小麦苗 小麦苗              3           6                 3                  6